265 research outputs found
Crassulacean Acid Metabolism in Three Species of the C4 Genus Portulaca
The putative existence of Crassulacean acid metabolism was investigated in three succulent species of the C4 genus Portulaca: P. grandiflora (a widely cultivated species), P. oleracea (a cosmopolitan weed), and P. mundula (found on rock outcrops throughout the southwestern United States). Patterns of diurnal conductance and CO2 exchange, as well as diurnal tissue malic acid fluctuations, were measured in plants under well-watered and drought-stressed conditions. Net CO2 uptake in both treatments occurred only during the day, although small amounts of nighttime CO2 uptake occurred in a few individuals. Stomatal conductances in well-watered and drought-stressed P. mundula and drought-stressed P. oleracea were higher during the night than during the day, though these higher conductances were generally not accompanied by net CO2 assimilation. No significant diurnal malic acid fluctuations occurred under well-watered conditions in any species; however, under drought stress, significant diurnal malic acid fluctuations occurred in the three species. The primary source of carbon for nocturnal malic acid production is presumed to be respiratory CO2, as occurs in C3 plants that undergo CAM-cycling. This study confirms past reports of CAM acid fluctuations in P. grandiflora and P. oleracea and marks the first report of CAM activity in P. mundul
Analysis of profit inefficiency in rice production in Eastern and Northern Uganda
Rice is among the emerging crops in Uganda that play an important role both as a food and a cash crop. It ranks fourth among the cereal crops in area cultivated, occupying a total of 80 thousand hectares of land with an estimated annual output of 120,000 metric tonnes. The study analyses sources of technical and allocative inefficiency and estimates the magnitude of profit losses and suggests policy interventions. A stochastic profit function and inefficiency function are estimated using cross-sectional data from a sample of 253 households from three districts of Eastern and Northern Uganda. The results show that rice farmers are not operating on the profit frontier. The main causes of inefficiency are firm-specific which include low education and limited access to extension services. These two factors have hampered the attainment of reasonable technical and allocative efficiency. From these results, it is clear that improvement in profit efficiency would require focused programmes to increase access to education and extension services
A Bima Array Survey of Molecules in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)
We present an interferometric search for large molecules, including methanol,
methyl cyanide, ethyl cyanide, ethanol, and methyl formate in comets LINEAR
(C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland
Association (BIMA) array. In addition, we also searched for transitions of the
simpler molecules CS, SiO, HNC, HN13C and 13CO . We detected transitions of
methanol and CS around Comet LINEAR and one transition of methanol around Comet
NEAT within a synthesized beam of ~20''. We calculated the total column density
and production rate of each molecular species using the variable temperature
and outflow velocity (VTOV) model described by Friedel et al.(2005).Considering
the molecular production rate ratios with respect to water, Comet T7 LINEAR is
more similar to Comet Hale-Bopp while Comet Q4 NEAT is more similar to Comet
Hyakutake. It is unclear, however, due to such a small sample size, whether
there is a clear distinction between a Hale-Bopp and Hyakutake class of comet
or whether comets have a continuous range of molecular production rate ratios.Comment: Accepted for Publication in the Astrophysical Journa
Allen Telescope Array Multi-Frequency Observations of the Sun
We present the first observations of the Sun with the Allen Telescope Array
(ATA). We used up to six frequencies, from 1.43 to 6 GHz, and baselines from 6
to 300 m. To our knowledge, these are the first simultaneous multifrequency
full-Sun maps obtained at microwave frequencies without mosaicing. The
observations took place when the Sun was relatively quiet, although at least
one active region was present each time. We present multi-frequency flux
budgets for each sources on the Sun. Outside of active regions, assuming
optically thin bremsstrahlung (free--free) coronal emission on top of an
optically thick ~10 000 K chromosphere, the multi-frequency information can be
condensed into a single, frequency-independent, "coronal bremsstrahlung
contribution function" [EM/sqrt(T)] map. This technique allows the separation
of the physics of emission as well as a measurement of the density structure of
the corona. Deviations from this simple relationship usually indicate the
presence of an additional gyroresonance-emission component, as is typical in
active regions.Comment: 16 pages, 11 figures. Accepted for publication in Solar Physic
The Medium Is the Danger: Discourse about Television among Amish and Ultra-Orthodox (Haredi) Women
This study shows how Old Order Amish and ultra-Orthodox women’s discourse about television can help develop a better understanding of the creation, construction, and strengthening of limits and boundaries separating enclave cultures from the world. Based on questionnaires containing both closed- and open-ended questions completed by 82 participants, approximately half from each community, I argue that both communities can be understood as interpretive communities that negatively interpret not only television content, like other religious communities, but also the medium itself. Their various negative interpretive strategies is discussed and the article shows how they are part of an “us-versus-them” attitude created to mark the boundaries and walls that enclave cultures build around themselves. The comparison between the two communities found only a few small differences but one marked similarity: The communities perceive avoidance of a tool for communication, in this case television, as part of the communities’ sharing, participation, and common culture
Oxaliplatin-dacarbazine combination chemotherapy for the treatment of advanced soft tissue sarcoma of the limbs
<p>Abstract</p> <p>Background</p> <p>This study was designed to explore the feasibility, safety, and outcomes of pre-operative oxaliplatin-dacarbazine combination therapy for the treatment of advanced soft tissue sarcoma (STS) of the limb.</p> <p>Patients and Methods</p> <p>Between November 2005 and November 2008, 31 patients with advanced limb STS classified with stage IV STS were randomly assigned into experimental or control groups, and both were given 2 cycles of chemotherapy before undergoing surgery. The regimen for the experimental group was oxaliplatin (120 mg/m<sup>2</sup>, d<sub>1</sub>) in combination with dacarbazine (175 mg/m<sup>2</sup>, d<sub>13</sub>), while that for the control group was a standard vincristine, epirubicin, cyclophosphamide therapy. Operations were carried out four weeks after the second chemotherapy cycle, followed by another 24 more chemotherapy cycles of the previous regimen.</p> <p>Results</p> <p>Following preoperative chemotherapy, the experimental group exhibited a significant improvement in tumor regression compared to controls. Both regimens were well-tolerated, and no significant differences in adverse reactions were noted. At a median follow-up of 24 months, 28 patients were still alive and had normal limb function. The progression free survival rate of the experimental group was significantly higher than that of the control group (10/15 vs. 4/16, <it>p </it>< 0.05).</p> <p>Conclusion</p> <p>Oxaliplatin- dacarbazine neoadjuvant/adjuvant chemotherapy improved the prognosis of patients with advanced limb STS in comparison with vincristine, epirubicin, cyclophosphamide combination therapy.</p
BIMA Array Detections of HCN in Comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4)
We present interferometric detections of HCN in comets LINEAR (C/2002 T7) and
NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland Association (BIMA) Array.
With a 25.4"x20.3" synthesized beam around Comet LINEAR and using a variable
temperature and outflow velocity (VTOV) model, we found an HCN column density
of N_T=6.4+-2.1x10^12 cm^-2, and a production rate of Q(HCN)=6.5+-2.2x10^26
s^-1, giving a production rate ratio of HCN relative to H_2O of ~3.3+-1.1x10^-3
and relative to CN of ~4.6+-1.5. With a 21.3"x17.5" synthesized beam around
Comet NEAT and using a VTOV model, we found an HCN column density of
N_T=8.5+-4.5x10^11 cm^-2, and a production rate of Q(HCN)=8.9+-4.7x10^25 s^-1,
giving a production rate ratio of HCN relative to H_2O of ~7.4+-3.9x10^-4 and
relative to CN of ~0.3+-0.2. For both comets, the production rates relative to
H_2O are similar to those found in previous comet observations. For Comet
LINEAR the production rate relative to CN is consistent with HCN being the
primary parent species of CN, while for Comet NEAT it is too low for this to be
the case.Comment: 20 pages, 2 figures, to be published in the Astrophysical Journa
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